here is what we know right now, the bombs were likely shrapnel-filled pressure cookers. investigators believe they may have been put in backpacks and may have been triggered by a type of timer. >> and for the first time today, president obama referred to the attacks that killed three and wounded 176 others as an act of terrorism. he went on to say that the american people refused to be

terrorized. tom sherwood has more on the stepped up security here in washington. we begin with tony tull who is live in boston close to where it happened. he tells us the tragedy also brought the city together. tony? >> reporter: and, good afternoon, the details are emerging still, we had an update earlier this morning, we'll hear from the fbi in an hour. one thing i noticed today, throughout the day the folks coming to the scene of the crime and just coming together. people who didn't know each other, people from other states and countries coming together and comforting each other. i just want to show you a sense of the scene, you can see a block away from boylston street, you can't see exactly where the bomb went off, but you can see here the folks who were supposed to celebrate, it has become a time where they will never forget. and you mentioned it, it is a time for them coming together.

>> everybody did exactly what they were supposed to do, this is a great city. >> reporter: the mood here in boston just blocks away from where the bombs exploded is still just disbelief. >> it was such a just xtapositi >> reporter: although he finished and beat his previous time, the events that took place yesterday took their toll. >> just being out in the street, getting out today and trying to come to terms with all of it. >> reporter: people walked by the scene and stopped to take in the sight, taking pictures and ems and police officers. just trying to gather any information or updates on the indication. mark mckinney walked around to let people know he was okay immediately after the bombing.

>> i don't know who you are, i don't know who the person i spoke to was, but he just wanted to let you know he is okay. >> reporter: later, the hours of comfort, the help was immeasurable. this lady was one of hundreds of people who opened their home if anybody needed a place to stay while they were helping family members getting treated. >> it just seemed like a good response to offer our house, whatever they needed after the marathon. >> jim, as you can imagine, the details still emerging, a lot of people are are coming to grips with what happened. as i said, acceptance is the theme here as people try to make sense. people are really, really hurting, coming together and comforting each other. >> tony, from a security stand tell us more about what you're seeing there around you, you

have a police zone, what are the police doing? has the security lessened over the day that you have been there? >> reporter: well, yeah, this morning they had about 12 blocks blocked off. we saw k-9s brought in, so we could assume they were trying to find other things around the building. i have to say we had over a thousand national guardsmen brought in from other states. we have multiple police, fbi, atfs, a lot of jurisdictions trying to assist, the fbi trying to figure out what is going on. a lot of street closures as you have mentioned. i have to tell you, we have police walking through the streets. there is a very big law enforcement presence here. >> and tony, are businesses closed in observance of the tragedy that happened there? or is it pretty much business as usual as it appears to be by the people we see walking behind

you. >> reporter: well, yesterday, a lot of the businesses around the area were closed within i would probably say ten blocks by ten blocks. a lot of them opened late this morning, we were walking down the street after the morning show, and a lot of them were trying to figure out what was going on. employees were too upset to figure out what happened. they were trying to figure out how to staff the restaurants. a lot of them are opened. business as usual, a lot of people here, they're runners and people getting into town. actually just leaving town. a lot of them still trying to figure out what they're going to do to get out of here. so i got to tell you, business as usual it may be, but i still have to say there is a sense of just insecurity in the city right now. >> it takes some time, news 4's tony tull on the scene live for us in boston, thank you so much tony. thank you, right now we're learning more about the two homemade bombs.

>> news team aaron gilchrist has more. >> reporter: the devices are being described as pressurer cooker bombs. these are not unfamiliar to law enforcement. according to somebody briefed on the explosion, the explosives were put in pressure cookers, hidden in bags and left on the ground. they were apparently packed with nails, shards, ball bearings, consistent with the injuries the doctors found yesterday. nbc news pete williams reported that the bombs were triggered by a timer as opposed to a remote detonator. we learned this type of bomb is frequently used in afghanistan and iraq, but also recently popped up in the u.s. one of the devices used in the times square attempted bombing was apparently a pressure cooker. now, we are hearing about a press conference at the top of the hour. we'll carry it live for you on

nbc 4 and nbcwashington.com. all right, thank you, aaron. and we're finding out more about the victims killed as the identities were revealed. three died yesterday, we now know two names, 29-year-old krystle campbell is one just confirmed to nbc news by her father this afternoon. she was a restaurant manager from medford massachusetts. this other guy, 8 years old, killed while they stood by the finish line. neighbors are haunted by this traged tragedy. >> to know he will never come home, it kept me up. >> martin released a statement, saying the wife and daughter suffered injuries, he asked others to pray for his family.

stay with us for continuing coverage, and coming up at 4:15, we'll have details about the work going on at the white house right now to bring the attackers to justice. you can always get the latest on our website at nbcwashington.com or check us out on facebook and twitter. right now, there are delays after computer problems grounded all american airlines flights. the problem happened after there were problems with the reservation systems. faa has asked they halt the flights until 5:00, reagan international has several cancelled flights from american right now. a teenage girl accused of sexting in northern virginia, why some say there was a double standard in the way she was published. >> everything was loud, i heard the explosion, called 911, i was waiting for the firefighters to come. the fight to reach three

college students trapped as the house went up in flames around them. and temperatures will continue to warm as we finish off the workweek. but cooler air arrives for the weekend. your complete forecast coming up

honoring the victims of virginia tech, the solemn

. >> neighbors in arlington say they watched as two women jumped from the second floor of a burning home. the fire started this morning along north dinwiddy street.

the flames were so intense it took more than 50 firefighters to get it under control. three people were home at the time. crews rushed two of them to the hospital with burns. the fire trapped a third person, samantha pazzo in the basement of the house. >> when i saw the smoke outside the door and i was trapped, i just had one exit, which was the back door. and the fire was in the back of the house. >> firefighters managed to get through the flames to rescue her. at this hour, northern virginia bureau reporter david culver is working the story. ahead on news 4 at 5:00 he will be live with more from the rescued woman including what she heard moments before the smoke filled her room. six years ago today, a student gunman went on the shooting rampage in virginia, leaving 32 dead. family and friends came to be there for a vigil outside the

nation's capitol. they held a moment of silence, then the name of each victim was read aloud. >> rachel elizabeth hill. age 18. richmond, virginia. emilie jane illshire. age 19. woodville, virginia. >> the gathering also included people who lost loved ones in the tucson, aurora and newtown shootings. the names of those victims were read aloud as well, this afternoon. the group also called for new gun laws to stop violence. it is video that is making the rounds on youtube. and it has led to allegations of police brutality. what started this confrontation between a father and police officer. and we'll take a look at the stepped-up security in

we want to update you now on the latest information coming from boston. at this hour, the investigators now say the type of bombs used in yesterday's terror attack at the marathon finish line were so-called pressure cooker bombs, packed with shrapnel and designed for maximum impacts. we have learned the identity of

one of the victims killed. 29-year-old massachusetts restaurant manager, krystle campbell, as well as martin richard, both killed yesterday. the area around is an active crime scene as the slew of law enforcement officials ask for the public's help to find clues about who is behind the terror attacks. meanwhile, the flags are at half staff. house speaker john boehner ordered the flags lowered to honor the bombing victims. and at the white house, this morning president obama ordered the u.s. flag to be lowered at federal buildings, military bases and embassies, throughout the world as a mark of respect for the victims. >> and he added he wouldn't stop until the attackers are brought to justice. and that his national security team has found no evidence that the attacks in boston were part of a broader terrorist plot. police are more on alert today, and right now. today they secured downtown

washington for the annual emancipation parade. >> the big public event took place less than 24 hours after the tragic bombing at the boston marathon. >> news 4 tom sherwood is live in downtown d.c. with the mood of parade-goers following this attack, tom? >> reporter: well, jim, the street festival connected with the emancipation day is still going on behind me. the police chief says there is more presence downtown, especially downtown. the annual emancipation parade drew a large crowd. there were no reported incidents and people said it was important to be out and about after boston. >> we were a little nervous, but i think if we give into that,

that helps o-- the bad people that did this, you know, we have to stay strong and show that we're not going to stop gathering people. because if we get to that point we won't go to any football games or basketball games. so i think it is a great sign that they came out to support the american people. >> reporter: now, coming up at 5:00, park police today briefly shut down the lincoln memorial. live in downtown washington, tom sherwood, news 4. all right, tom, we'll check back in at 5:00. the blast delayed last night's episode of "revolution" in case you were watching. we want viewers to know it will air next monday at 10:00. the rest of the scheduled episodes will move back a week so you wouldn't miss a thing on the drama. turning back to the weather, the sunshine a welcome thing. yes, after a cloudy start to the day the clouds broke up, a really pleasant evening across the area, temperatures in the 70s, great night for the soccer

game, taking the dog for a walk? beautiful picturesque scene as we take a live look outside at the water. and again, just a great evening to go for a nice walk. temperatures will continue to warm through friday. as we finish off the work week we're going to warm the 80 degrees, so another week we'll run above average. rain moving through the area, late friday. maybe early saturday. and that is going to cool us down for the weekend. satellite and radar image right now showing just a few scattered clouds across the area. again, temperatures presently in the 70s. and for the evening hours, expect temperatures in the mid-to-upper 60s. so nice and warm. southerly wind at 10 to 15 miles an hour. helping to bring some warmer air into the area. for tomorrow morning on your wednesday, you could be dealing with some fog as you make your way into work. so you do want to remember that. otherwise it will be a comfortable start to the day. grab a jacket by the late afternoon, you may not need it.

mostly sunny skies tomorrow, temperatures between 55 and 60 degrees. now, you can see here at 7:00 a.m., we're dry, mostly cloudy skies. but as we work our way into the afternoon hours can't rule out a few widely scattered showers. maybe even a rumble of thunder in culpeper. working our way through the evening hours, mostly cloudy, a good portion of the area should be mainly dry. again, details for tomorrow afternoon, light showers possible. maybe even a thunderstorm south. otherwise, mostly sunny skies and a broad temperature range from 70 to areas to the north of d.c., down to 80 for areas to the south.

you can see fredericksburg, culpep culpeper. the 30% chance of showers, thursday, keeping it dry with mostly cloudy then partly cloudy skies as the day wears on. for friday, rain will move through later in the day so a dry start. look at the weekend, pat and jim. 63 degrees for saturday and sunday. so a big temperature cooldown to come for the weekend. but sunday, plenty of sunshine. >> all right, thank you, amelia. sure thing. a good samaritan attacked. what happened to a woman he was trying to help out. and in northern virginia, a

. let's go to aaron gilchrist at the live desk with an update on the glitch that shut down american airlines. >> reporter: pat, just getting word that american airlines says the computer system is back up after the glitch that happened about 1:00 this afternoon. there was a problem with the computer that handled recollection reservations and check-ins, they were grounded all over the country until the problem was resolved. now word the computer system is back up and running. it will be about 45 minutes before american can put things back into motion.

and so people should expect lots of delays with american airlines across the country for the next few hours to come. that is the latest from the live desk, i'm aaron gilchrist. thank you, aaron. allegations of police brutality at rohoga beach, how a baby moon ended with the father being tasered. and what police say about the video. also, we're expecting a news conference about the terror attack in boston, in the next half hour, we'll bring it to you li

. a search that will go on to the ends of the earth.

that is what the fbi is saying about the effort to find the people responsible for the terror attack in boston. this, as we learn new details about the attacker's weapons. welcome back to news 4 at 4:00, i'm pat lawson. and i'm jim handly. now we're expecting a news conference in boston to begin in about 30 minutes and will britain it bring it to you live right now. investigators still have nobody in custody, despite searching the town of revere overnight. jay gray has more on the investigation, and new firsthand accounts from people who were at the finish line. >> reporter: hey, there, good evening, pat, jim, more than ten square blocks still locked down as the investigators search for the suspect causing the blast. there is a high intensity security blanketing boston right now. this evening, there is an

awkward, ominous silence in the city, military vehicles taking the place of thousands who had packed the marathon overnight. a day after the deadly bombings, boston is on high alert. >> everyone should expect continued heightened police presence and everybody should expect police to continue to be vigila vigilant. >> reporter: the explosives were packed with pressure cookers, explosives packed into duffle bags loaded with shrapnel, designed for maximum impact. >> the other objects are a small nail, carpenter type, small in diameter. >> reporter: victims described the effects. >> i looked over at my wife. and you know, i see that her lower leg was hit by something. you know, some shrapnel had hit

her leg. and you know, she was bleeding. >> reporter: an attack now officially characterized as an act of terrorism. >> what we don't yet know, however, is who carried out this attack or why. whether it was planned and executed by a terrorist organization, foreign or domestic, or was the act of a malevolent individual. >> reporter: our mission is clear, to bring to justice those responsible for the bombing, justice for those killed, including 8-year-old martin richard, whose mom and sister suffered serious injuries after the attack. the family honored with candles and a posted memorial on social websites. part of a growing memorial, to honor the victims. tonight there is a ceremony at a local church, while tomorrow the center will hold an inner-faith ceremony to honor all the

victims of the attack, jay gray, news 4. over the past decades in the country, our country has witnessed more terror attacks, and more than 150 people died in oklahoma city, when a blast happened. a year later, the blast at the olympic games in atlanta, killing two, wounding others. and the worst in history, of course, 2001, september, when the al-qaeda operatives crashed the planes into the world trade center, the pentagon and in pennsylvania. stay with us for continuing coverage of the boston bombings. coming up in moments we'll hear from a psychologist on how to process tragic events like this one. a home invasion in loudoun county. aaron gilchrist has more from the live desk. >> reporter: a scary moment for a family in taylorstown, loudoun, virginia. this is chopper 4 above the scene, the home invasion robbery

happened about 11:30 this morning on loyalty road in taylorstown, virginia, as we hear from the loudoun county sheriff's office, four men apparently entered this home. they held the family at gunpoint, went through their things, took some items and then took off. now, nobody was hurt in the incident but right now deputies and investigators are canvassing the scene here as you see it below the chopper, the house here as well as the rest of the neighborhood. they are looking for anything that could have been dropped, any type of evidence that could track the people should responsr the robbery. nobody was hurt in the incident and the sheriff's office would like us to know that we should expect to see an increased police presence in the area as they investigate through the evening, that is the latest from the live desk, i'm aaron gilchrist. we get the story from paul the 6th, in fairfax.

>> reporter: the website jezebel first put allegations out there, claiming a female student here at paul the 6th catholic high school was forced to withdraw from the school after allegedly sending inappropriate pictures of herself to other boys in the school. somehow, those pictures got shared around. now parents are wondering whether others should be punished. paul the 6th catholic high school prides itself on instilling academies and rich values. but the 30-year-old school is now dealing with a moral dilemma. there are accesses that a female student was forced to withdraw. coming after she allegedly shared an inappropriate photo of herself with other male students. they, in turn, are accused of sharing it with friends. for their part, they will not release specifics on how they handled the incident. but one source said not the believe everything they read, especially over the internet. and that there are always two sides to every story.

the diocese of arlington, michael donohugh e-mailed me, saying it did not accurately reflect the event. i spoke with several parents outside the school today. they didn't want to go on camera, but they say for the most part they feel very confident on how the school handled the situation. they feel the on-line reports were over exaggerated. i spoke to the fairfax county police. a lot of folks asked why weren't they involved. they said they would not comment on the investigation because it is a juvenile matter. i'm david culver, news 4. and family and friends gathered here at st. mary's catholic church in rockville today to pay their final respects to michelle miller. police found the 17-year-old dead last week inside the home of an army recruiter. they say staff sergeant adam

arndt shot her before killing himself. she went to his house after he called to say he was depressed. and the good deed that ended with a woman attacked in

. northeast d.c. woman was just trying to help a guy out. now, he is accused of sexually assaulting her.

the attack happened early sunday morning in the woman's home on lincoln road. so far there have been no arrests. as news 4 pat collins reports, it all started with a knock at the door. >> anybody knocks on my door, i don't answer it. because anybody who belongs in my home has a key. >> reporter: that is retina christian. she has lived in this neighborhood a long time and she is most upset by what happened here. we'll hear more from her and other neighbors later. it happened in the 1900 block of lincoln road northeast, around 4:00 a.m. they say the woman had just returned home from a night out. she was inside her apartment when she hears a knock on her door. on the other side of the door is a man. he says he needs her help. he says he needs to use her

phone. so she lets him in. and once inside, they say, he rapes her. and then runs away. now back to neighbor retina christian. she says the good samaritan days are over. >> you just can't do that anymore. you just can't let people in your home anymore. you know, those days have been gone. they left here with my mom, you know, who is close to 80. those days are gone, part. >> reporter: reaction now from some other neighbors. >> she shouldn't have opened the door and should have asked who was it. there isn't anything else i can say. >> reporter: can't be too careful? >> you can't. >> it is good to be good samaritans but sometimes you have to be really careful and cautious. >> you don't open the door to anyone, i don't care whatever. you just don't open the door to anyone. i don't.

>> reporter: i'm pat collins, news 4. how to cope with tragedy. we get some advice from professionals today about how to deal with traumatic events like the attack in boston. and for tomorrow, areas to the north of d.c. will be in the low 70s, south, upper 70s. what about rain another upda

terror attack in boston, we are awaiting a press conference from the fbi to get the latest on the investigation, which is scheduled to start 15 minutes from now, we'll bring you it live when it happens. meanwhile, the number of people injured is 176, three people were killed, including krystle campbell and 8-year-old martin richard, still no suspects in custody, the president is pledging to find those responsible. >> we'll take time to determine every lead and find out what happened. but we will find out and find whoever harmed or citizens and we will bring them to justice. >> president obama also ordered flags to be flown at half staff through saturday evening. >> we now know more about the man behind one of the most

iconic images of the marathon bombing. video of the first blast showed -- >> the explosion sounded like a bomb went off, the shock waves just hit my body. >> iffrig suffered a scrape and was abl to finish in his age division, pat? watching tragedies like the boston bombing is disturbing for most people. many people can't help but feel empathy for the victims and fear for their own safety. erika edwards talked to them about processing the horrible

event events. >> reporter: all the people could do was watch, stunned. >> your natural capacity as a human being is to feel other people's pain. >> reporter: psychologists say the explosion in boston can trigger a sort of nationwide ptsd, and bring up other tragedies like 911 or the bombing in atlanta's centennial park. >> it almost feels like we cannot relax or get comfortable and contented about violence. it is so prevalent. and that is what is so -- i think discomforting to most people. >> reporter: perhaps most heartbreaking about this story is that a child is among the dead. helping other children cope with that news depends on their age. many experts recommend limiting kids' media exposure and reassure them that while sad these events are rare. >> kids of all ages take their cues from us as parents.

and so the more emotional we are about it, the more aware and concerned the kids will likely be. >> reporter: there are signs that the nation is trying to heal. candles lit, neighbors sharing images of love for boston. >> when people don't know what else to do they tend to sort of put their heart stamp on social media. and i think it is a great way for people struggling to be able to go there and realize they're not alone. >> reporter: perhaps the best way to cope is to remember there is something about the nation's worst moment that can bring out the best in its people. erika edwards, news 4. and stay with us for the continuing coverage on the terror in boston, we'll continue the live team coverage from bean town, and visit nbcwashington for more eyewitness accounts and the latest information as it comes in. new developments right now in the immigration reform battle. aaron gilchrist is at the live desk.

>> reporter: just moments ago the president wrapped up a meeting with senators john mccain and chuck schumer who went to the white house to talk about the immigration reform plan they're working on. the president reduleased a statement saying the bill is a compromise but largely is consistent with the principles he has laid out for comprehensive immigration reform. noting that it would strengthen security at the borders and provide a pathway to earned citizenship for undocumented immigrants in the country. he urged the senate to move forward with the bill so that some meaningful immigration reform can be seen by the american public soon. that is the latest from the live desk, i'm aaron gilchrist. all right, amelia is back with the latest on the weather. and the pollen feels high out there. we don't know. >> and it is high, especially if you are affected by trees, tree pollen continues to be high. in the forecast if you're an allergy sufferer, not much for the rest of the week. the temperatures right now are simply beautiful.

there is a live look outside, you can see the sun coming out after a cloudy start on this tuesday. as we look to tomorrow we'll tarrant once again with clouds and maybe some limited sunshine tomorrow afternoon. but look at where our temperatures have climbed to, with the help of the sun. we're now at 71 in washington, 73 in gaithersburg. 77 for those of you in leesburg, manassas, and la plata, 7:00, we're pleasant, 70, not too cold as we get to the 11:00 hour as well, tonight. temperature at 11:00 will be around 63 degrees, starting off the wednesday. comfortable start, but there could be some areas of fog. temperatures tomorrow morning between 55 and 60 degrees. by the afternoon, we're looking at temperatures ranging from 70 degrees for areas in northern maryland. and then around 80 down in portions of virginia and southern maryland. and you could be dealing with a shower, mainly tomorrow

afternoon, maybe even a rumble of thunder for those of you around culpeper, fredericksburg, and charlottesville. frederick hitting 69, culpeper, 70. here is the allergy forecast, ash, birch, elm and pine, the allergy forecast is continuing to be high through the rest of the week. tomorrow, the forecast, 73, 30% chance of an afternoon shower. thursday, mix of clouds, sun, 80 on friday, rain arrives later in the day. a breezy day, a mild day, 60 degrees saturday and sunday, maybe rain early for your saturday. plenty of sunshine on sunday, and a chance of rain for you next monday. back to you. all right, thank you, amelia. a home daycare provider in alexandria had her license suspended after she was found with seven children in her vehicle.

not one of them was in a proper safety seat. as the bureau reported the woman and some parents who used her services hope she can stay in business. >> i know that it was wrong. but i had an emergency. >> reporter: that is alexandria home daycare provider betty ross, talking about the incident late last week that could cost her the license to operate. ross says she was caring for four children at her town house last week when she learned her mother was taken to the hospital. she loaded kids in the vehicle to pick up sandy louis, a friend who helps watch the children sometimes. she picked up four more children. when they stopped to eat, somebody called the police. ross and a friend in the front seat, a child seated between them, another child on ross's lap. three more kids were in the back seat. and two were in the cargo section of the suv. louis says there was only a child on ross's lap once they stopped the vehicle. the toddler had been bitten and

she was comforting the child. >> the way they portrayed it, it is harsh, but not as harsh as they're making it to be. people make mistakes, this is a terrible mistake that we're going to have to go through and get to. >> reporter: ross is charged with seven counties of contributing to the delinquency of a minor. one charge has been dropped. ross continues to provide care to one child, but alexandria residents say they have suspended they are license. this little go who usually goes to betty's daycare stayed with her mom this time. but she hopes she doesn't lose her license. >> i love her to be at ms. betty's house. >> reporter: ross is hopeful that since she has had no other incidents in her eight years of providing care she can remain open. >> if they let me keep my license, i'll do what i have to do, better, for next time.

>> betty ross is due back in court in may. a vacation that ended with accusations of police brutality. the confrontation that happened in rahova beach, making the rounds today. and coming up more on the terror attack in boston, we'll carry it for you live. and concerns from doctors today that women are not being properly treated for a deadly kind of

be sure to watch us on facebook

and twitter. images of what appearing to be brutality on the part of rahova beach police is getting attention. >> yes, the father was tasered several times, the baby was said to have become a nightmare. >> hi, can i just take him home. >> reporter: >> reporter: in an exclusive interview, 34-year-old jeremy anderson of mechanicsburg said he didn't deserve this treatment from rahova beach. he said this incident happened over a room key. >> he tasered me in the chest. he -- i fell to the ground. he shot me with a dart in the

back. tasered me multiple times in the spine. >> reporter: when anderson's wife, candace arrived, she turned on the cell phone camera, hearing him ask police to stop. >> i was honor frrifyhorrified. >> you hear me in the video. >> reporter: anderson was arrested, charged with disorderly conduct, resisting arrest, and offensive touching of law enforcement. he spent two nights in jail before candace posted a $7,000 bond. when they arrived back home, doctors told anderson he had a concussion. >> i had severe head pain, back pain, my nerves are shot. >> we need an apology from the rahova police department and the city. >> reporter: they're also asking the officers seen in the video to be relieved of their duties. while at the anderson home, the rahova police chief keith banks returned our phone call for conduct of the officers. he says an investigation is

under way. >> be assured that we take these things very seriously, regarding use of force. >> reporter: do you think that your officer used excessive force based on what you saw on youtube? >> i just want to be fair to all sides. and not comment what i think. >> reporter: monique braxton, nbc news. and when asked about tourists in the upcoming summer season, the chief welcomed everybody to what he called a safe, clean town. >> he said the officers involved are still on the job tonight. tonight at 5:00. >> this was a heinous and cowardly act. and given what we know knew took place, the fbi is investigating it as a terrorist activity. >> reporter: the major investigation in full swing and

the nation on high alert. the latest now into the probe on the deadly twin bombings. good evening, i'm jim handly. i'm pat lawson, it has been a little over 20 hours since the blast at the finish line at the iconic race. this evening the shock waves still continuing. people gather with heavy hearts while federal investigators are looking for clues. >> we are also learning about the device that killed three and injured more than 150 others. at least three are in critical condition. the so-called pressure cooker bombs contained ball bearings and metal fragments, meant to cause harm to people. doctors have been asked to catalogue and save the items. and investigators say there also may have been recovered a circuit-board detonator. investigators questioned one